The history of civilization reveals that Man's destiny is controlled by geology. Rivers provide water, food, transportation, construction materials, and protection. Waterfalls provide sites where power can be developed. Flooding delivers new sediment to the croplands and destroys Man's structures. The right combination of geology and climate develop fertile soil profiles, which support a successful agricultural base for the economy. Mountainous terrains are usually underdeveloped when compared to the “flat lands” because the geologic processes are more hostile and the soils are poorly developed. It took population pressure or the automobile and a modern “leisure” society to bring Man to the mountains in great numbers. The existence of such natural resources as gold, silver, or coal produce short-lived, boom cities in the mountains that decline as soon as the resource is depleted. The successful modern city was originally sited because a balance of geologic factors related to agricultural commodities, water supply, transportation, and natural resources exists. Cheap energy, following industrialization introduced suburban living and caused the city to expand into areas having unfavorable and hazardous geologic conditions or into areas containing the resources necessary for the city's growth. Thus, modern cities face a conflict: the need to grow versus exposure to unfavorable or hazardous natural processes. If this conflict is to be resolved, and modern Man is to be provided with a safe place to live and work, it is imperative that physical constraints and opportunities be defined so that geology once again is the foundation of the city.